DE 10 2006 021 802, as a later published document, relates to the control of a passive prosthetic knee joint with adjustable damping in the direction of flexion such that a prosthetic appliance, with upper attachment means and with a connection element to an artificial foot, which is secured on the prosthetic knee joint, can be adapted for climbing stairs. The low-torque lift of the prosthetic foot is detected, and the flexion damping in the lift phase is then reduced to below a level that is suitable for walking on a plane.